This invention relates to a frame structure comprising two compound units provided with mutually facing grooves undercut on either side, in which the first compound unit can be attached in a desired position to the second compound unit via a detachable coupling, which consists of a turning part which can be turned from the outside manually via a handle about its longitudinal axis by about 90.degree. into its coupling or decoupling position, engages positively in its coupling position by means of a T-head at its one end in one of the two grooves and by means of anchoring means at its other end in the other of the two grooves and can be locked in this coupling position by means of an anti-rotation device.
Such an arrangement is described in Swiss Pat. No. 580,210, which discloses a facade structure in which one compound unit is a flatly configured cover profile overlapping at least one plate element, in the groove of which cover profile the turning part is held by its T-head, while the other compound unit is a post profile, in the groove of which the turning part engages by two parallel fork arms, which are provided with snap-in lugs, and thus effect an anchorage in the undercut groove. The turning part consists of at least two parts which can be turned relative to each other, one of which bears the T-head and the other the parallel fork arms. The two parts are held together by at least one screw forming the common axis. The part of the turning part provided with the T-head has opposite areas for fitting a wrench. With the aid of a wrench, this part can therefore be turned relative to the other part. It is also possible, however, for a handle to be molded as an integral component on the T-head part for turning this part. The fork part is fixed in the groove of the post profile by pressing in, if necessary by a blow. The screw is fixed, for example cast, in the T-head part. By turning the T-head part, the screw is turned further into the fork part and thereby exerts a spreading pressure on the fork arms and thus secures the fork part against dropping out.
This structure is complex to manufacture and assemble and does not offer adequate reliability against unintended detachment of the turning part.